Conventionally hydrogen gas is widely stored, for example, by compressing hydrogen gas and filling in a flask, or by storing in a hydrogen absorbing alloy or hydrogen absorbing material capable of storing hydrogen.
As well as the above hydrogen absorbing alloys and the like, hydrogen storage glass capable of storing hydrogen is also known as a hydrogen storage material. Specifically, disclosure has been made of storing hydrogen in fine hollow glass spheres, and releasing the stored hydrogen by applying heat and light thereto (see, for example, “Photo-Induced Hydrogen outgassing of glass”, Douglas B. Rapp and James E. Shelby, Journal of Non Crystalline Solids 349 (2004), pages 254 to 259).
However, since hydrogen is a colorless and odorless gas, it is generally very difficult to detect hydrogen leakage. Accordingly, in order to detect hydrogen leaks, a component for odorizing hydrogen (referred to below as an odor agent) is mixed with the hydrogen.
Generally, when the odor agent is mixed in, odor is added to the hydrogen by mixing the odor agent directly into the gaseous hydrogen. However, when the stored hydrogen is released, the strength of the smell needs to be controlled according to the amount of hydrogen released. Conventionally, either the strength of the smell is not controlled, or, in order to adjust the strength of smell, a new component such as a control valve for controlling the concentration was used when the odor agent is mixed in.
Even when using the above described hydrogen storage glass, the hydrogen diffuses out since the hydrogen storage glass contains small pores. However, large molecules like those of the odor agent are not able to permeate through these pores. In terms of results, the hydrogen storage glass does not control the strength of smell, or it is needed to provide a new separate component for control.
Hydrogen absorbing alloys are capable of absorbing hydrogen, but are not capable of absorbing the odor agent together with hydrogen by absorbing the odor agent.